1. Field of the Invention
The present invention relates generally to the field of semiconductor chip packaging and, more particularly, to chip scale packaging (CSP) with improved heat dissipation capability.
2. Description of the Prior Art
Chip scale packaging (CSP) has been introduced into the packaging industry for years to reduce overall volume of an electronic terminal product. CSP is typically referred to the post-package chip module, which is nearly the same size of the semiconductor chip such as a dynamic random access memory (DRAM) chip.
FIG. 1 demonstrates a sectional schematic view of a conventional chip scale packaging (CSP) module. As shown in FIG. 1, the conventional CSP module comprises a chip or die 10 that is adhered to a first side 15 of a packaging substrate 14 through an adhesive layer 12. The packaging substrate 14 has a central opening 16 exposing input/output pads 18 of the chip 10. Through the gold wires 19, the input/output pads 18 of the chip 10 are electrically connected to the corresponding bonding pads 20 disposed on the second side 17 of the packaging substrate 14. The input/output pads 18, gold wires 19, bonding pads 20 are protected with resin that fills the through hole 16. On the second side 17 of the packaging substrate 14, a number of solder balls 26 are implanted thereon. A resin passivation 32 seals the chip 10.
The above-described CSP module utilizes a single-layer packaging substrate 14. That is, metal pattern is merely formed on one side (the second side 17 in the case) of the packaging substrate 14, which is opposite to the packaged chip 10. No metal layer is formed on the other side (the first side 15) of the packaging substrate 14. Typically, the heat conductivity coefficient of the packaging substrate 14 is no more than 0.37 W/m° C. In operation, it becomes problematic because heat produced by the chip 10 cannot be efficiently dissipated through the packaging substrate 14 or a printed circuit board where the CSP module mounted.
In light of the above, there is a need in this industry to provide an improved CSP module with enhanced heat dissipation capability, thereby improving chip performance.